The present invention relates generally to clocks with striking mechanisms for striking a chime, gong, or the like on the hour, half-hour, or quarterly fractions of the hour, such a clock being hereinafter called a chime clock. More particularly, the present invention relates to a chime clock in which the minute hand shaft is rotatable in both clockwise and counterclockwise senses.
Typically, a chime clock comprises a cam mounted directly on the clock's minute hand shaft to rotate with the minute hand shaft. The cam comprises a step or plurality of steps, corresponding to the hour, half-hour or quarterly fractions of the hour. A cam follower, connected to a striking mechanism, is positioned to ride along the peripheral edge of the cam, and, at the precise moment when a chime or other sound is required, the cam follower drops off a step on the cam, thereby actuating the striking mechanism to strike a chime, gong or the like. Structure for accomplishing the striking or chiming function is disclosed in more detail in said parent application Ser. No. 671,143, the disclosure of which has been incorporated herein by reference.
The minute hand shaft, together with the chime-controlling cam mounted thereon, conventionally rotates in a clockwise sense. It is sometimes desirable for the minute hand shaft to be capable of rotating in a counterclockwise sense. For example, when setting the minute hand of a chime clock, a person may try to turn the minute hand backwards, and this would urge the minute hand shaft in a counterclockwise sense. If the minute hand shaft was connected to other parts of the clock in such a manner that it could not be readily rotated in a counterclockwise sense, a person could damage the clock by trying to force the minute hand backwards.
In chime clocks having a striking mechanism of the type described in said parent application Ser. No. 671,143, the cam follower and related structure interfere with rotation of the minute hand shaft in a counterclockwise sense. More specifically, as the chime-controlling cam is rotated in a counterclockwise sense, the cam follower comes into engagement with the edge of a step on the cam, obstructing further rotation in a counterclockwise sense of the cam and minute hand shaft. As previously described, this could lead to damage to the clock mechanism when an unsuspecting person attempts to set the clock by turning the minute hand backwards.